In the early 1980s, Tom Kirkwood developed the International Normalized Ratio to standardise prothrombin time reporting. The INR reduced dangerous variation between laboratories using different thromboplastins. It became the global language for monitoring warfarin therapy.

The standardization of the International Normalized Ratio (INR) in 1983 transformed the management of anticoagulation therapy. For poets living with this reality, the INR became a symbol of survival, capturing the daily negotiations of health, fear, and reassurance in their writing.